chore: 添加虚拟环境到仓库

- 添加 backend_service/venv 虚拟环境
- 包含所有Python依赖包
- 注意：虚拟环境约393MB，包含12655个文件

backend_service/venv/lib/python3.13/site-packages/sympy/utilities/mathml/__init__.py

@@ -0,0 +1,122 @@
+"""Module with some functions for MathML, like transforming MathML
+content in MathML presentation.
+
+To use this module, you will need lxml.
+"""
+
+from pathlib import Path
+
+from sympy.utilities.decorator import doctest_depends_on
+
+
+__doctest_requires__ = {('apply_xsl', 'c2p'): ['lxml']}
+
+
+def add_mathml_headers(s):
+    return """<math xmlns:mml="http://www.w3.org/1998/Math/MathML"
+      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+      xsi:schemaLocation="http://www.w3.org/1998/Math/MathML
+        http://www.w3.org/Math/XMLSchema/mathml2/mathml2.xsd">""" + s + "</math>"
+
+
+def _read_binary(pkgname, filename):
+    import sys
+
+    if sys.version_info >= (3, 10):
+        # files was added in Python 3.9 but only seems to work here in 3.10+
+        from importlib.resources import files
+        return files(pkgname).joinpath(filename).read_bytes()
+    else:
+        # read_binary was deprecated in Python 3.11
+        from importlib.resources import read_binary
+        return read_binary(pkgname, filename)
+
+
+def _read_xsl(xsl):
+    # Previously these values were allowed:
+    if xsl == 'mathml/data/simple_mmlctop.xsl':
+        xsl = 'simple_mmlctop.xsl'
+    elif xsl == 'mathml/data/mmlctop.xsl':
+        xsl = 'mmlctop.xsl'
+    elif xsl == 'mathml/data/mmltex.xsl':
+        xsl = 'mmltex.xsl'
+
+    if xsl in ['simple_mmlctop.xsl', 'mmlctop.xsl', 'mmltex.xsl']:
+        xslbytes = _read_binary('sympy.utilities.mathml.data', xsl)
+    else:
+        xslbytes = Path(xsl).read_bytes()
+
+    return xslbytes
+
+
+@doctest_depends_on(modules=('lxml',))
+def apply_xsl(mml, xsl):
+    """Apply a xsl to a MathML string.
+
+    Parameters
+    ==========
+
+    mml
+        A string with MathML code.
+    xsl
+        A string giving the name of an xsl (xml stylesheet) file which can be
+        found in sympy/utilities/mathml/data. The following files are supplied
+        with SymPy:
+
+        - mmlctop.xsl
+        - mmltex.xsl
+        - simple_mmlctop.xsl
+
+        Alternatively, a full path to an xsl file can be given.
+
+    Examples
+    ========
+
+    >>> from sympy.utilities.mathml import apply_xsl
+    >>> xsl = 'simple_mmlctop.xsl'
+    >>> mml = '<apply> <plus/> <ci>a</ci> <ci>b</ci> </apply>'
+    >>> res = apply_xsl(mml,xsl)
+    >>> print(res)
+    <?xml version="1.0"?>
+    <mrow xmlns="http://www.w3.org/1998/Math/MathML">
+      <mi>a</mi>
+      <mo> + </mo>
+      <mi>b</mi>
+    </mrow>
+    """
+    from lxml import etree
+
+    parser = etree.XMLParser(resolve_entities=False)
+    ac = etree.XSLTAccessControl.DENY_ALL
+
+    s = etree.XML(_read_xsl(xsl), parser=parser)
+    transform = etree.XSLT(s, access_control=ac)
+    doc = etree.XML(mml, parser=parser)
+    result = transform(doc)
+    s = str(result)
+    return s
+
+
+@doctest_depends_on(modules=('lxml',))
+def c2p(mml, simple=False):
+    """Transforms a document in MathML content (like the one that sympy produces)
+    in one document in MathML presentation, more suitable for printing, and more
+    widely accepted
+
+    Examples
+    ========
+
+    >>> from sympy.utilities.mathml import c2p
+    >>> mml = '<apply> <exp/> <cn>2</cn> </apply>'
+    >>> c2p(mml,simple=True) != c2p(mml,simple=False)
+    True
+
+    """
+
+    if not mml.startswith('<math'):
+        mml = add_mathml_headers(mml)
+
+    if simple:
+        return apply_xsl(mml, 'mathml/data/simple_mmlctop.xsl')
+
+    return apply_xsl(mml, 'mathml/data/mmlctop.xsl')